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U.S. Department of Energy
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Progress in the ICF Program at the Lawrence Livermore National Laboratory

Conference ·
OSTI ID:5841499

Experiments using the harmonically converted Nd:glass lasers at the Lawrence Livermore National Laboratory (Novette with 2 to 10 kJ at 0.26 and 0.53 micron and Nova with 30 to 80 kJ at 0.35 and 0.53 micron) have demonstrated favorable coupling of laser light to fusion targets. The coupling of short-wavelength laser light to these plasmas is now well understood and is primarily collisional in nature, in contrast to previous experiments at 1.06 microns and 10 microns, where the coupling was collective. Increased absorption and conversion to x-rays and decreased production of suprathermal electrons was measured with decreasing wavelength. Stimulated Raman scattering was identified as the primary source of the suprathermal electrons. The collisionality of the laser target coupling can be controlled by the proper selection of laser wavelength and target material. The coupling improvements led directly to the demonstration of higher-density ablative implosions of DT fusion fuel. Experiments on Novette demonstrated a better than 100-fold compression of the DT fuel with two-sided illumination. The Nova laser is extending laser-plasma studies to plasmas several times larger than those used on Novette. Recent experiments have produced a yield of over 10/sup 13/ neutrons. Temporally shaped pulses on Nova will be used to compress DT fuel close to the 200 g/cm/sup 3/ densities ultimately required for high-gain target performance.

Research Organization:
Lawrence Livermore National Lab., CA (USA)
DOE Contract Number:
W-7405-ENG-48
OSTI ID:
5841499
Report Number(s):
UCRL-94321; CONF-860551-5; ON: DE86010945
Country of Publication:
United States
Language:
English